You mean caseless, Hi-C Plastic rounds in a chem seales clip? Expensive but nearly undetectable.
I carry an Elan with those on every single char.
Capsule rounds in chem seals are just as undetectable.
But if you fill 'em with DMSO'd Slab, Narcoject, Gammascopolamine, Novascorpion Venom or Ringu if you can get your hands on it... They're a LOT more effective than those plastic or ceramic bullets.
Problem is: my GM tends to "borrow" such ideas and use them against us some time later, so I'll keep the Hi-C rounds I think 
Speaking AS a GM: "if it's good for the goose, it's good for the gander"
And that exactly is the reason not a single one of my characters owns a burst-fire-modded Thunderstruck Gauss rifle.
Even though I REALLY like the idea ... and the design ... and that thing is pure awesomeness 
not sure if you could hit anything with a burst fire Thunderstruck... seeing as HMGs and assault cannons double uncompensated recoil... and the only thing you can really use on a magnetic accelerated weapon would be a gyro mount.....
Give you props for the sheer "OMG WTF?!!?!!" factor though 
I guess tripods would help too, as would Electronic Firing, Heavy Barrel, Underbarrel Weight (at least according to RAW) ... and then there is the 25 dice to roll for the attack plus taking aim (the one character I REALLY want that for is a Longe Range Fire Support Specialist).
I can live with that for 12P with AP/half - 4 
had some time on my hands and I read the take Aim on page 148 SR4a.... says nothing about the firing mode of the shot (SS, SA, BF, FA) so I imagine you could use "take Aim" and then fire a burst.
However, reading the Assault cannon entry again, they DOUBLE the recoil, not the uncompensated recoil (big difference), then in an other area they say Uncompensated recoil (huh? um, conflict there??) But at least with the Uncompensated recoil entry, they provide an example.
Some things to note and remember about recoil mods to are:
[Arsenal book page 148 bold facing by me]
Restrictions to Recoil Compensation
Not all methods of recoil compensation are cumulative in
their effect:
• Recoil compensation from an auto-adjusting weight, bipod,
foregrip, gyromount, sling, tripod, or underbarrel weight are
not cumulative with each other (except that the compensation
from a foregrip and sling can be combined into an overall
recoil compensation of 2).
• Recoil compensation from a folding stock, hip pad, rigid
stock, shock pad, or sling are not cumulative with each other
.
• Recoil compensation from a gas-vent system is not cumulative
with that from any other gas-vent system.
• Recoil compensation from electronic firing and personalized
grip are not cumulative with each other.
• Recoil compensation from a heavy barrel is cumulative with
all other recoil compensations
Oh, and I was wrong again about something (imagine THAT!)
[Arsenal book page 29, bold facing by me]
All machine guns and assault cannons can be equipped with
top-, barrel-, and under barrel mounted accessories, unless otherwise
noted. They cannot use silencers or sound suppressors and
suffer from double recoil modifiers (see Recoil, p. 142, SR4). Firing
these weapons requires the Heavy Weapons skill.
and the entry for the thunderstuck says nothing about barrel mods...